Skywarn® is a proactive spotter network. During severe weather outbreaks, the NWS activates Skywarn®, and spotters in target areas are notified. Skywarn® spotters are then asked to relay observances from locations near potential trouble spots. Volunteer ham radio operators staff a station at the weather service office, receive weather information from ham radio operators throughout the region, and forward them to the NWS forecasters..